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https://issues.apache.org/jira/browse/DAFFODIL-2843?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17764798#comment-17764798
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Mike Beckerle commented on DAFFODIL-2843:
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I took a look at the code.
LayerException is never caught, but the the only usage is for
LayerNotEnoughDataException which is caught and converted to a PE when parsing.
LayerException are ThinDiagnostics so don't carry a stack trace. They are
intended for use in processing errors that might be frequent on account of
backtracking/speculative parsing.
So one flaw is that we're only catching LayerNotEnoughDataException when we
should be catching LayerException.
I believe LayerException should be renamed to LayerProcessingException, where
the "ProcessingException" suffix is intended to mean the DFDL interpretation of
that term, which is a parse or unparse error.
LayerExecutionException is just a RuntimeException, which is just the usual
re-encapsulation of whatever the real exception is as the cause of the
LayerExecutionException.
Probably should be renamed to LayerFatalException as this is always a bug
indication.
I think the approach is this: the layer transformer code itself should be
responsible for converting any exception into some kind of
LayerProcessingException which is caught and becomes a parse error when
parsing, unparse error when unparsing.
For example, suppose the gzip layer code throws a a null pointer exception on
certain bad data cases. Then the gzip layer transformer should catch NPE and
convert to a LayerProcessingException and throw that.
Any other exception thrown from a layer transformer is either unavoidable (Like
a Java JVM out-of-memory exception), or is a bug in the layer that it wasn't
anticipated and caught. These are what turn into a LayerExecutionException
which is essentially a bug indication.
> Unclear how to create Parse/UnparseError from ParseOrUnparseState
> -----------------------------------------------------------------
>
> Key: DAFFODIL-2843
> URL: https://issues.apache.org/jira/browse/DAFFODIL-2843
> Project: Daffodil
> Issue Type: Bug
> Components: Back End
> Affects Versions: 3.5.0
> Reporter: Olabusayo Kilo
> Priority: Major
>
> It is unclear how to create a parse/unparse error using ParseOrUnparseState
> while creating a layer transform. Currently we can create a SDE using
> ParseOrUnparseState, but there are situations where the issue is with the
> data, not the schema.
> A possible workaround is to manually recreate what PE and UE do as in:
> {code:scala}
> parserOrUnparseState match {
> case pstate: PState => // do what PE(...) does
> case ustate: UState => // do what UE(...) does
> }
> {code}
> Related to DAFFODIL-2841
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